Marine vessels and, more particularly, tugboats and ferry boats are well known. A tugboat, or tug, is a boat used to maneuver, primarily by towing or pushing, other marine vessels in harbors, over the open sea or through rivers and canals. They are also used to tow barges, disabled ships, or other equipment like tow boats. Further, they are used to extinguish fires in water locations where land equipment cannot perform fire fighting operations.
Presently, tugboats are powered by diesel engines. One disadvantage of diesel engines is that they emit a large amount of pollutants and, more particularly, compounds that contain carbon such as carbon dioxide. Another disadvantage is that they consume a large amount of fuel while performing routine tag boat operations. Another disadvantage is that the use of diesel engines requires a large space for the drive lines in the tugboat. Still another disadvantage is that diesel engines are very noisy and contribute to elevated levels of noise pollution.
According to the present invention, a drive system for a tugboat is provided utilizing a combination of stored energy batteries and diesel powered generators. The diesel generators are only used in the towing mode, that is when the tugboat is attached to a vessel, fire fighting mode or when charging the batteries.
The use of stored energy batteries dramatically reduces carbon emission while meeting or exceeding the functionality, safety and power requirements of present day tugs. Such reduction can be as high as 90 percent when compared to the present power drive designs. Further the use of stored energy batteries substantially reduces power consumption, the drive line space requirements and the noise level.
These and other advantages and objects of the present invention will become apparent from the following description.